Android application design considerations

Many a times, developers are given/shown a copy of a Web Application or an existing iPhone application and are asked to design or provide and estimate to port/create a similar application for Android. Since, the platforms have significant changes, this task becomes very tricky. Apart from highlighting and convincing the management about differences in platform, what can a developer do to ensure that estimates are reasonable enough and his job of creating such an app becomes less painful? Does your book talk about design considerations that a developer needs to make before starting with an web-based Android application?